CSM recovery for normal and abnormal termination

For normal or abnormal termination, CSM users free all owned buffers prior to completing termination processing. However, this might not always be possible for abnormal termination.

To ensure that buffers are not lost as a result of normal or abnormal termination, CSM uses the following resource termination managers to reclaim buffers that are owned by the terminating environment:

Job Step Task Resource Termination Manager: Job Step Task cleanup is performed if task is not an MVS™ started task (for example, batch).
Memory Resource Termination Manager: Memory cleanup is performed whenever address space memory termination occurs.

The resource managers perform the following actions:

Receive control from recovery termination management (RTM) during job step task and memory termination processing
Determine if any of the allocated buffers are owned by the terminating address space
As appropriate, free the buffers back to the buffer pool

Additionally, CSM allows the user to associate buffers to a task. Buffers that are task-associated are reclaimed by CSM at the end of the specified task only if the task abnormally terminates. The user of the buffer is responsible for ensuring the buffers are freed during normal termination.

If a CSM user wants to provide recovery mechanisms to free buffers at events other than those provided by CSM, the user can create ESTAE/FRR recovery routines to recover at a program level or RESMGR to create a resource manager to recover at a task termination event not provided by CSM. When performing this type of processing, users must ensure that their application processing is properly synchronized with any applications to which they are passing buffers.